Jump to content
Dr. Odenwald

Smartphone Detection of geomagnetic storms

Recommended Posts

I am completing an investigation of how well the common smartphone platform might be as a detector of geomagnetic storms as classified by the common Kp scale. I will post my results here from time to time, and would like to invite you all to help me 'crowdsource' any upcoming storms so that I can improve my estimates of detectability along the Kp scale. The problem is that this is being undertaken as we approach sunspot minimum so the really strong storms with Kp > 6 may be few and far between!

  • Like 3

Share this post


Link to post
Share on other sites

I was told the smartphone is not sensitive enough to detect changes in the earths magnetic field, I have been trying experiments s with my ipad and it dont seem to change at all since its not measuring in nT but in micro tesla

Edited by Brian Murphy Slattum
typo
  • Like 1

Share this post


Link to post
Share on other sites

Hi Marcel and Brian!

Great to see you are interested in this.

My first analysis shows that the Samsung Note 5 is superior to the iPhone 6s. They use two different magnetometer chips and clearly the Samsung chip is far more stable and generates fewer data artifacts. Also the iPhone magnetometer is much more temperature sensitive over a range from 40 to 80 F.   In terms of geomagnetic storm detectability, I still do not have good statistics on events stronger then Kp=5 so it is not clear that I have reached a sensitivity threshold for detecting storms yet. The data so far for conditions between 1 < Kp < 5 the performance of both platforms seems to be consistent with noise ,dominated not by the ADC limit at +/- 0.16 nT, but by uncontrollable systematic drifts and artifacts for which it is hard to create a measurement protocol that reduces their effects.  Sadly, I missed the big September Storm, and the statistics are not good for another major event with Kp>6 or 7 this late in the sunspot cycle. I plan to publish these results in a journal at some point but it would really be great to get one actual storm under my belt to prove the concept!!!

To the specific points you raised,

Marcel, being in a remote location would be ideal of course, but so long as you are 5 meters from any obvious surface metals in buildings or other em interference, it does not seem to matter, but of course more will be known as I get better observations.

Brian,  It is not obvious to me that smartphones cannot detect changes, but in the next month I will be doing some absolute calibration measurements here at NASA/Goddard to see what the dB/dT threshold is for these chips. Of course it is the change in B over time that correlates with Kp not just static measurements of Bz.  With the absolute calibration against professional-grade magnetometers I should be able to pretty well quantify the performance of the magnetometer chips in these two platforms.

 

  • Like 1

Share this post


Link to post
Share on other sites

Ok, I have now completed my smartphone study using an iPhone 6S and a Samsung Note 5.

It looks like the Samsung platform has the better magnetometer sensor, but both platforms seem to be insensitive to storms weaker than about Kp=5. I was able to catch one storm at Kp=8 on September 8, 2017 when I was just beginning my study with the iPhone but not the Note 5, unfortunately. If it takes a storm with a Kp> 7 to be detected by smartphone technology ca 2015, it is possible that newer models will have better and more sensitive magnetometer sensors. As it stands, the tested smartphones only convincingly register the rare, strong storms and not the more numerous weaker ones.

I have written this research up and expect to publish it in the American Geophysical Union Journal of Space Weather later this year.

  • Like 1

Share this post


Link to post
Share on other sites

That's a great result! Congratulations! Did you get similar readings between the smartphone and a professional magnetometer? Good to know that you got a result and the data wasn't hindered by any outside influences.

Share this post


Link to post
Share on other sites

Interesting, hopefully future phones will be better at this. What would be cool is something that could predict local substorms. I'm usually stuck in a city that happens to be around the KP2 viewing line, though I prefer using the NOAA hemispheric power model as my strength indicator. Many nights a camera with a wide aperture lens will pick up a faint green haze that the eye can't see at around 15GW. I have spent many nights outside but only recently got a substorm that was bright and active over the light pollution that lasted 2 minutes at 22GW. Being able to predict these local storms would be a game changer for people stuck in cities to see Northern Lights. 

  • Like 1

Share this post


Link to post
Share on other sites

I think I would be detecting a Kp=7 in my head before a smartphone would!

Surely, the problem is not one of absolute sensitivity of the sensor, but its ability to isolate 'domestic' magnetic noise changes from natural variations.  I operated a jamjar magnetometer (read: mirror stuck to a bar magnet suspended on a thread) once in a field about 300m from a minor road.  It was swamped by passing cars - and even they were pretty few and far between at night.

I'm not convinced the smartphone is a good idea.  There are so many internet-linked magentometers now that one is much better informed by alerts from any one - or several - of those.  Or just by being environmentally aware and looking out the door!

 

 

  • Like 1

Share this post


Link to post
Share on other sites

Welcome John. I would agree with John. While I have no idea if it is possible or not to detect geomagnetic storms with a smartphone, I can imagine it is not an ideal way. The magnetometers that I know of at least are buried under the ground to prevent any kind of outside influences. Even temperature differences can upset the readings.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you also agree to our Terms of Use and our Privacy Policy.